A mobile phone of lately is designed in compact size in order to facilitate carrying thereof. The more convenient for the user to carry the mobile phone, the smaller the dimension should become. In order to eliminate the bulky size, some mobile phones are designed in foldable types (generally known as flip-phone). Referring to FIGS. 1A and 1B, a conventional mobile phone 10 is shown to include a lower casing 108, an upper casing 102 connected pivotally to the lower casing 108, and an antenna unit 112 projecting outwardly from the lower casing 108 for receiving and transmitting the radio signals. The upper casing 102 is provided with a minor window 104 via which suspending mode of the conventional mobile phone 10 can be observed. The upper casing 102 is turnable from the folded position shown in FIG. 1A to the unfolded position shown in FIG. 1B, in which, the upper casing 102 reveals a major window 106 to display the inputted information when the keypad 110 is operated.
In the aforesaid conventional mobile phone, means to prevent untimely and undesirable transmission is provided due to accidental actuation of the keypad 110. The preventing means includes a magnet member (not visible) disposed within the upper casing 102 and a sensor (not visible) provided in the lower casing 108 such that the sensor generates a circuit closing signal upon sensing the approach of the upper casing 102 relative to the lower casing 108. Under this condition, any inputted signal will not be processed when the mobile phone is at the folded position.
It is noted that the sensor is relatively slow to respond the approach of the upper casing so that undesired actuation of the keypad to generate transmission of signals is still possible. In addition, employment of the sensor, the magnetic member and the cost of writing software result extra manufacturing expense.
In order to eliminate the aforesaid disadvantage, a stopper is formed on the lower casing of another conventional mobile phone so as to space the keypad apart from the upper casing when at the folded position. Since the stopper, generally made from plastics or rubber, is susceptible to wearing and therefore succumbs to wearing and results in loss of its ability after a long period of use.